[WATCHDOG] Add w83697h_wdt early_disable option

Pádraig Brady requested the possibility of not disabling the watchdog
at module load time or kernel boot time if it had been previously enabled
in the bios. It may help rebooting the machine if it freezes before the
userland daemon kicks in.
Signed-off-by: Samuel Tardieu <sam@rfc1149.net>
Cc: Pádraig Brady <P@draigBrady.com>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>

drivers/watchdog/w83697hf_wdt.c

@@ -44,6 +44,7 @@
 #define WATCHDOG_NAME "w83697hf/hg WDT"
 #define PFX WATCHDOG_NAME ": "
 #define WATCHDOG_TIMEOUT 60		/* 60 sec default timeout */
+#define WATCHDOG_EARLY_DISABLE 1	/* Disable until userland kicks in */
 
 static unsigned long wdt_is_open;
 static char expect_close;
@@ -62,6 +63,10 @@ static int nowayout = WATCHDOG_NOWAYOUT;
 module_param(nowayout, int, 0);
 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
 
+static int early_disable = WATCHDOG_EARLY_DISABLE;
+module_param(early_disable, int, 0);
+MODULE_PARM_DESC(early_disable, "Watchdog gets disabled at boot time (default=" __MODULE_STRING(WATCHDOG_EARLY_DISABLE) ")");
+
 /*
  *	Kernel methods.
  */
@@ -178,6 +183,22 @@ wdt_disable(void)
 	spin_unlock(&io_lock);
 }
 
+static unsigned char
+wdt_running(void)
+{
+	unsigned char t;
+
+	spin_lock(&io_lock);
+	w83697hf_select_wdt();
+
+	t = w83697hf_get_reg(0xF4);	/* Read timer */
+
+	w83697hf_deselect_wdt();
+	spin_unlock(&io_lock);
+
+	return t;
+}
+
 static int
 wdt_set_heartbeat(int t)
 {
@@ -394,7 +415,11 @@ wdt_init(void)
 	}
 
 	w83697hf_init();
-	wdt_disable();	/* Disable watchdog until first use */
+	if (early_disable) {
+		if (wdt_running())
+			printk (KERN_WARNING PFX "Stopping previously enabled watchdog until userland kicks in\n");
+		wdt_disable();
+	}
 
 	if (wdt_set_heartbeat(timeout)) {
 		wdt_set_heartbeat(WATCHDOG_TIMEOUT);